org.objectweb.asm.commons

Class AdviceAdapter

public abstract class AdviceAdapter extends GeneratorAdapter implements Opcodes

A MethodAdapter to insert before, after and around advices in methods and constructors.

The behavior for constructors is like this:

as long as the INVOKESPECIAL for the object initialization has not been reached, every bytecode instruction is dispatched in the ctor code visitor
when this one is reached, it is only added in the ctor code visitor and a JP invoke is added
after that, only the other code visitor receives the instructions

Author: Eugene Kuleshov Eric Bruneton

Field Summary
protected int	methodAccess
protected String	methodDesc

Constructor Summary
protected	AdviceAdapter(MethodVisitor mv, int access, String name, String desc) Creates a new AdviceAdapter.

Method Summary
protected void	onMethodEnter() Called at the beginning of the method or after super class class call in the constructor.
protected void	onMethodExit(int opcode) Called before explicit exit from the method using either return or throw.
void	visitCode()
void	visitFieldInsn(int opcode, String owner, String name, String desc)
void	visitInsn(int opcode)
void	visitIntInsn(int opcode, int operand)
void	visitJumpInsn(int opcode, Label label)
void	visitLabel(Label label)
void	visitLdcInsn(Object cst)
void	visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
void	visitMethodInsn(int opcode, String owner, String name, String desc)
void	visitMultiANewArrayInsn(String desc, int dims)
void	visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels)
void	visitTypeInsn(int opcode, String type)
void	visitVarInsn(int opcode, int var)

Field Detail

methodAccess

protected int methodAccess

methodDesc

protected String methodDesc

Constructor Detail

AdviceAdapter

protected AdviceAdapter(MethodVisitor mv, int access, String name, String desc)

Creates a new AdviceAdapter.

Parameters: mv the method visitor to which this adapter delegates calls. access the method's access flags (see Opcodes). name the method's name. desc the method's descriptor (see Type).

Method Detail

onMethodEnter

protected void onMethodEnter()

Called at the beginning of the method or after super class class call in the constructor.

Custom code can use or change all the local variables, but should not change state of the stack.

onMethodExit

protected void onMethodExit(int opcode)

Called before explicit exit from the method using either return or throw. Top element on the stack contains the return value or exception instance. For example:

   public void onMethodExit(int opcode) {
     if(opcode==RETURN) {
         visitInsn(ACONST_NULL);
     } else if(opcode==ARETURN || opcode==ATHROW) {
         dup();
     } else {
         if(opcode==LRETURN || opcode==DRETURN) {
             dup2();
         } else {
             dup();
         }
         box(Type.getReturnType(this.methodDesc));
     }
     visitIntInsn(SIPUSH, opcode);
     visitMethodInsn(INVOKESTATIC, owner, "onExit", "(Ljava/lang/Object;I)V");
   }

   // an actual call back method
   public static void onExit(int opcode, Object param) {
     ...

Custom code can use or change all the local variables, but should not change state of the stack.

Parameters: opcode one of the RETURN, IRETURN, FRETURN, ARETURN, LRETURN, DRETURN or ATHROW